Got one hole pretty well finished - now to duplicate 5 more times

Are you going to measure flow when you're done?  At least to balance the six, maybe not actual CFM numbers.  A mismatch in flow could make tuning difficult since the ECU (CU?) assumes equal flow.  

That would be the ideal scenario , but maybe not realistic for me. Lots of measurements and eyeballing is about the best I will do. I will be measuring combustion chambers to make sure they are equal.


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I've thought that a person might be able to make a simple comparative manometer using a shop vac and clear hose in a u-shape.  Fill the hose with water and set up a Bernoulli type system to pull the water up.  Make marks and you can compare each set of ports and runners.  No numbers just seeing if they pull the same.

A good vacuum gauge might be precise enough to get some good readings also.  Or a pressure gauge on the inlet side of a blower, instead of a shop vac.  Won't show flow but would allow one to one comparisons.

I have actually considered something like that , but never have implemented it. Now in the middle of building a new shop I'm lucky to get anything done

Well I can actually say I’m making progress again. Wanting more power for this summer and getting my Megasquirt going has been a big motivator. The block has been sitting under plastic bags and the guts have been in Tupperware totes.

I had already sized rings so they were ready to go. I had to clean the pistons again for the third time after noticing i missed some carbon in the ring glands. I also drilled out the plugs on the block to get full access to the oil gallery. After getting that done it was time to clean again. 

Id say assembly went smoothly but had issues with oil clearances on 4&5 mains. All the caps were numbered and marked with dots( which I did neither to the best of my memory) . I put it back the same way and 4 had only .001 clearance while 5 had .003. I tried everything from deburring, filing , swapping bearing shells to improve things and nothing worked. When 4 got torqued , it made the crank noticeably harder to turn. I finally had to resort to calling my machinist for advice. He said to try swapping caps, and I did , and it worked. Crank spun freely and plastic gauge showed .002 on both. That was a big victory ! I knew this engine spun freely when I took it apart , but didn’t pay attention to the markings other than that they were marked. 

Piston pop out is .023 . Yes the block was shaved . 

Waiting on a timing kit to come in since I wasn’t happy with the Melling kit. Dam crank sprocket would even fit ?

Time to dust off the MN47 . It’s been sitting in a box for a very long time and I wasn’t even sure how much more work it needed. I considered using my E88 that’s on my L24 , but at 37cc Chambers , I think it would be too much CR, besides the fact .050 has been shaved off it and makes P2V clearance much less. 

The MN47 needs more port work around the guide area mostly, then dropping in bigger intake valves , so it will take a minute . But it will get most of my attention for a while . With block pretty much done , I can concentrate on the head . 

Steve....Did you decide on a Cam yet? If you are still interested in my new Isky Stage II, I’ll let her go. I’ve got two Stage III backups, so I won’t be needing it. $195.00 .....I’ll pay shipping.

Guy

Edited February 6, 20187 yr by Diseazd

What’s the rpm power band on that stage 2?

its probably too small for what I want . What are doing with all those 3’s

Them 3’s are staying in Virginia....the 2 is a .480 lift 280 duration....not sure about the power band.

More progress - finally I am satisfied with the combustion chambers and head in general , so time to measure . MN47 are said to have 39cc chambers , but I beg to differ. 41.2 cc right now with bigger valves and head surfaced at least .015. I did unshroud the chambers which I gained some there, but it wasn’t a lot.

No cam picked out yet , but I have springs. I will still probably drill and tap the coolant passages on 2-6 cylinders . The marks are there already , so I’ll just finish what Nissan started.

 

On 2/6/2018 at 12:36 PM, madkaw said:

 

 

That picture should make people think about some of the published Data on some of the Flat Top pin. heights. I've always contested that the OZDat engine calculator has got the pin height wrong, as it calculates the piston crown as being below the deck surface. Same as the dished pistons. That is obviously incorrect. 

Very common for FT' to stick above the block deck approx 0.021" to 0.024" .  And why you always check dimensions.... 

I don't like that OZDAT either but for another reason, too complicated for me. 

I like this one,  http://www.240260280.com/legacy/techtips/calcs/engine builder/index.html

ozdat has block height at 207.85

240260280 has 207.87

Looking back at those numbers I made a mistake apparently because it seems bassackwards now???  I'm not the shiniest valve in the head.

Edited September 27, 20186 yr by siteunseen